Some thoughts. First, there is a spring involved, the hammer spring. The varying tension on these springs will effect touch weight. Second, Inertia, or mass, is far lighter than on a grand piano. Third, the greater mass of the key will be on the back side, not the front end of the key. I have no idea of this consequence but it is an interesting thought. I think strike weight will have a far lower effect on touch and tone than on a grand. 50% more on the other hand may well be outside any tolerance range. I would suggest trimming the width of the hammers somewhat to get them into the ball park, say 10 to 15%. Hammer spring tension can have a profound effect on tough weight, far more than most other elements. I think I would go for basic balance weight and check the key weights. Then check without the springs. Do the inertia weighing first, adjust balance weight by spring tension then voice and hope you get something "reasonable". How you will adjust spring tension on hammer springs I have no idea. Sorry. Let us know what you do, what you experiment with and the end result. Lots of luck. Newton
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